Timer



A. E. SMITH.

TIMER.

APPLICATION FILED SEPT. 12, 1919.

Patented Mar. 15, 1921.

FIG. 2

lNVE/V TOP? ATTOPN E Y W/TNESSES UNITED STATES PATENT OFFICE.

ALBERT E. SMITH, OF MILWAUKEE, WISCONSIN, ASSIGNOR, BY DIRECT AND MESNEASSIGNMENTS, TO MILWAUKEE AUTO ENGINE AND SUPPLY COMPANY, OF MIL-WAUKEE, WISCONSIN, A CORPORATION OF WISCONSIN.

TIMER.

Specification of Letters Patent.

Patented Mar. 15, 1921.

To all whom it may concern:

Be it known that I, ALBERT E SMITH, a citizen of the United States, andresident of Milwaukee, in the county of Milwaukee and State ofWisconsin, have invented new and useful Improvements in Timers, of whichthe following is a description, reference being had to the accompanyingdrawings, which are a part of this specification.

The invention relates to timers or distributers for internal combustionengines for making and breaking the ignition'circuits to the ignitiondevices of the engine.

In the usual construction of timer, a movable brush cooperates with thecontacts of the commutator which contacts have a straight joint with theinsulating material of the commutator so that the brush travels all onthe contact or all on the insulating material. In practice the contactsof this type of commutator start pitting near the jointafter a shorttime and this pitting gradually wears a groove into the contact near itsbreak end which causes an uneven action of the brush as it travels overthe contact and limits the period of eflicient operation of the timer,so that the commutator has to be frequently renewed. The presentinvention is designed to overcome this difficulty by providing acommutator in which each of the contacts set into the insulatingmaterial has a break end of such a character as to permit the brush toride both on the insulating material and on the contact during thebreaking. By this construction I have found that the pitting at thebreak end of the contact gradually works back as far as the main bodyportion of said contact while the insulating material adjacent thisbreak end Wears down, and by the time the pitting has reached the bodyportion of the contact, then the previous pitted surface of the contactand the insulation have been worn down so as to bring the whole portionof the break end again into active operation. Furthermore, in thisgradual wearing down process the brush or roller will be carried overany pitted portion of the break end by the insulating material uponwhich it rides.

The fact that the brush rides partly on the break end of the contact andpartly on the fiber at the time of breaking the circuit, prevents anuneven action of the brush even though the end of the contact be pitted,and the extended or narrowed break end of the contact saves the mainbody portion of the contact from pitting and'causes a smooth action ofthe roller on the track formed by the commutator.

The invention further consists in the several features hereinafter setforth and more particularly defined by claims at the conclusion hereof.

In the drawings: F ignre 1 is a sectional view through the timer showingthe device embodying the invention; Fig. 2 is a detail verticalsectional view through the commutator embodying the invention.

The commutator 3 is mounted in a casing & and is in the form of a ringof insulatmg material 5 having contacts 6 inset therein and formingtherewith a continuous circular trackway 7 upon which runs a brush 8.This brush is here shown in the form of a roller but it may be a slidingshoe or any other suitable form of contact moved over the track 7 tosuccessively engage the contacts of the commutator. As here shown theroller 8 is carried by a lever 9 pivotally mounted intermediate its endsupon an arm 10 secured to the timing shaft 11, said lever being moved bya spring 12 to hold the roller against the track, all of which brushconstruction is well known. The invention resides in the contact and itsarrangement with reference to the insulating material of the commutator.The break end 13 of each contact where it oins with the insulatingmaterial of the trackway is narrower than the width of the main bodyportion of the contact and preferably gradually decreases in width froman imaginary line 14 to its end 15, thus forming an angular extensionfrom the main body portion of the contact. However, I desire it to beunderstood that this narrowed break end of the contact may be ofdifferent forms than the one specifically shown so long as the brushwhen leaving the main body portion of the contact rides partly on thecontact and on the insulating material during the breaking.

I'Vith the construction herein shown I have pitted end has worn down tosuch an extent that the roller again rides both on this end and thefiber and all parts wear down together and then the action of pittingfrom the end 15 to the line 14 is again repeated after a certain period.Thus, even though pitting occurs at the break end of the contact, theefficient action of the timer isnot impeded and the commutator contactscan be used fora much longer period of time than those in the usual formof timer.

In the drawings I have shown the joint between'the .contact 6 and theinsulating material at the make end 16 as being straight because at thisend there is no sparking and consequently no liability for pitting, butif such a condition should occur the make end of the contact may alsohave a portion projected out from the main body of the contact so thatthe brush rides partly on the insulating material and "partly on themake end of the contact for a brief period.

It is to be understood that this invention is not limited to anyspecific form or arrangement of parts, except in so far as saidlimitations are specified in the claims.

What I claim as new and desire to secure by Letters Patent is:

1. In a timer, the combination, with a contact roller, of a commutatorcooperating therewith comprising insulating material and spaced contactsinset therein to form a track for the roller, each of said contacts atits break end being of less width than the main body ortion of thecontact so that the brush during breaking 'rides partly on the contactand partly upon the insulating material.

2. In a timer, the combination of a commutator comprising an insulatingmember and spaced contacts inset therein to form a track therewith, acontact roller running on said track, each. of said contacts at itsbreak end having a projection from the that the roller during breakingrides partly on the contact and partly upontthe insulating material.

In testimony whereof, I afiix my signature;

ALBERT E. SMITH.

